title: Effect of subinhibitory concentrations of four commonly used biocides on the conjugative transfer of Tn916 in Bacillus subtilis.
abstract: OBJECTIVE
  Large amounts of biocides are used to reduce and control bacterial growth in the healthcare sector, food production and agriculture. This work explores the effect of subinhibitory concentrations of four commonly used biocides (ethanol, hydrogen peroxide, chlorhexidine digluconate and sodium hypochlorite) on the conjugative transposition of the mobile genetic element Tn916.
  
  
  METHODS
  Conjugation assays were carried out between Bacillus subtilis strains. The donor containing Tn916 was pre-exposed to subinhibitory concentrations of each biocide for a defined length of time, which was determined by an analysis of the transcriptional response of the promoter upstream of tet(M) using β-glucuronidase reporter assays.
  
  
  RESULTS
  Ethanol significantly (P = 0.01) increased the transfer of Tn916 by 5-fold, whereas hydrogen peroxide, chlorhexidine digluconate and sodium hypochlorite did not significantly affect the transfer frequency.
  
  
  CONCLUSIONS
  These results suggest that exposure to subinhibitory concentrations of ethanol may induce the transfer of Tn916-like elements and any resistance genes they contain.
authors.affiliation: Division for Epidemiology and Microbial Genomics, National Food Institute, Technical University of Denmark, Kgs. Lyngby, Denmark.
authors.forename: M A
authors.initials: MA
authors.lastname: Seier-Petersen
authors.forename: A
authors.initials: A
authors.lastname: Jasni
authors.forename: F M
authors.initials: FM
authors.lastname: Aarestrup
authors.forename: H
authors.initials: H
authors.lastname: Vigre
authors.forename: P
authors.initials: P
authors.lastname: Mullany
authors.forename: A P
authors.initials: AP
authors.lastname: Roberts
authors.forename: Y
authors.initials: Y
authors.lastname: Agersø
mesh_terms: D001412:Bacillus subtilis / Q000187:drug effects* / Q000235:genetics*; D003227:Conjugation, Genetic / Q000187:drug effects* / Q000235:genetics*; D004202:Disinfectants / Q000008:administration & dosage*; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods; D016896:Treatment Outcome
chemical_list: D004202:Disinfectants
keywords: Tn916; chlorhexidine digluconate; ethanol; hydrogen peroxide; resistance gene transfer; sodium hypochlorite